cmake.mk: add support for overriding the source dir, and define the cmake prefix path to avoid picking up host libraries for target builds (patch by Henning Rogge)

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@34914 3c298f89-4303-0410-b956-a3cf2f4a3e73

include/cmake.mk

@@ -4,6 +4,8 @@ ifneq ($(findstring c,$(OPENWRT_VERBOSE)),)
   MAKE_FLAGS+=VERBOSE=1
 endif
 
+CMAKE_SOURCE_DIR:=.
+
 ifeq ($(CONFIG_CCACHE),)
  ifeq ($(CONFIG_EXTERNAL_TOOLCHAIN),)
   CMAKE_C_COMPILER:=$(TOOLCHAIN_DIR)/bin/$(TARGET_CC)
@@ -53,8 +55,9 @@ define Build/Configure/Default
 			-DCMAKE_STRIP=: \
 			-DCMAKE_INSTALL_PREFIX=/usr \
 			-DDL_LIBRARY=$(STAGING_DIR) \
+                        -DCMAKE_PREFIX_PATH=$(STAGING_DIR) \
 			$(CMAKE_OPTIONS) \
-		. \
+		$(CMAKE_SOURCE_DIR) \
 	)
 endef